Electromagnetic Waves | Physics JEE Main questions with Solutions

Q 1 :

Arrange the following in the ascending order of wavelength:

A. Gamma rays ( $λ_{1}$ )

B. x-rays ( $λ_{2}$ )

C. Infrared waves ( $λ_{3}$ )

D. Microwaves ( $λ_{4}$ )

Choose the most appropriate answer from the options given below [2024]

$λ_{4} < λ_{3} < λ_{1} < λ_{2}$
$λ_{2} < λ_{1} < λ_{4} < λ_{3}$
$λ_{4} < λ_{3} < λ_{2} < λ_{1}$
$λ_{1} < λ_{2} < λ_{3} < λ_{4}$

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(4)

Order of wavelength

gamma rays < x-rays < infrared < microwaves

$\Rightarrow λ_{1} < λ_{2} < λ_{3} < λ_{4}$

Q 2 :

Match List-I with List-II:

List-I

(EM-Wave)

List-II

(Wavelength Range)

A Infra-red (I) $10^{- 3}$ nm

B Ultraviolet (II) 400 nm to 1 nm

C X-rays (III) 1 mm to 700 nm

D Gamma rays (IV) 1 nm to $10^{- 3}$ nm

Choose the correct answer from the options give below [2024]

(A)-(I), (B)-(III), (C)-(II), (D)-(IV)
(A)-(IV), (B)-(III), (C)-(II), (D)-(I)
(A)-(III), (B)-(II), (C)-(IV), (D)-(I)
(A)-(II), (B)-(I), (C)-(IV), (D)-(III)

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(3)

Infrared is the least energetic thus having biggest wavelength $(λ)$ and gamma rays are most energetic thus having smallest wave length $(λ)$ .

Q 3 :

Arrange the following in the ascending order of wavelength ( $λ$ )

(A) Microwaves ( $λ_{1}$ ) (B) Ultraviolet rays ( $λ_{2}$ )

(C) Infrared rays ( $λ_{3}$ ) (D) X-rays ( $λ_{4}$ )

Choose the most appropriate answer from the options given below: [2025]

$λ_{4} < λ_{3} < λ_{2} < λ_{1}$
$λ_{3} < λ_{4} < λ_{2} < λ_{1}$
$λ_{4} < λ_{2} < λ_{3} < λ_{1}$
$λ_{4} < λ_{3} < λ_{1} < λ_{2}$

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(3)

Q 4 :

Given below are two statements: One is labelled as Assertion (A) and other is labelled as Reason (R).

Assertion (A) : Electromagnetic waves carry energy but not momentum.

Reason (R) : Mass of a photon is zero.

In the light of the above statements, choose the most appropriate answer from the options given below: [2025]

(A) is true but (R) is false.
(A) is false but (R) is true.
Both (A) and (R) are true but (R) is not the correct explanation of (A).
Both (A) and (R) are true and (R) is the correct explanation of (A).

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(2)

EM wave carry both energy and momentum. Restmass of photon is zero.

Q 5 :

If an optical medium possesses a relative permeability of $\frac{10}{π}$ and relative permittivity of $\frac{1}{0.0885}$ , then the velocity of light is greater in vacuum than that in this medium by _______ times. ( $μ_{0} = 4 π \times 10^{- 7} H / m, \in_{0} = 8.85 \times 10^{- 12} F / m, c = 3 \times 10^{8} m / s$ ) [2025]

(6)

Since velocity of light in terms of $μ$ and E is

$v = \frac{1}{\sqrt{μ ε}} = \frac{1}{\sqrt{μ_{0} μ_{r}}} \times \frac{1}{\sqrt{ε_{0} ε_{r}}} = \frac{1}{\sqrt{μ_{r} ε_{r}}} \times \frac{1}{\sqrt{μ_{0} ε_{0}}}$

$v = \frac{c}{\sqrt{μ_{r} ε_{r}}} = \frac{c}{\sqrt{\frac{10}{π} \times \frac{1}{0.0885}}} = \frac{c}{\sqrt{36}} = \frac{c}{6}$

$\Rightarrow c = 6 v$

Velocity of light in vacuum is greater by 6 times the velocity of light in medium.

Q 6 :

The electric field and magnetic field components of an electromagnetic wave going through vacuum is described by $E_{x} = E_{0} \sin (k z - ω t), B_{x} = B_{0} \sin (k z - ω t)$ . Then the correct relation between $E_{0}$ and $B_{0}$ is given by [2023]

$E_{0} B_{0} = ω k$
$E_{0} = k B_{0}$
$k E_{0} = ω B_{0}$
$ε E_{0} = ω B_{0}$

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(3)

$C = \frac{ω}{k} = \frac{E_{0}}{B_{0}}$

Q 7 :

Match List-I with List-II. [2023]

List I List II

A. Microwaves I. Physiotherapy

B. UV rays II. Treatment of cancer

C. Infra-red rays III. Lasik eye surgery

D. X-rays IV. Aircraft navigation

Choose the correct answer from the option given below:

A-II, B-IV, C-III, D-I
A-IV, B-I, C-II, D-III
A-IV, B-III, C-I, D-II
A-III, B-II, C-I, D-IV

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(3)

(Theoretical)

A. Microwaves → IV B. UV rays → III

C. Infra-red rays → I D. X-rays → II

Q 8 :

Match the List-I with List-II: [2023]

List I List II

A. Microwaves I. Radio active decay of the nucleus

B. Gamma rays II. Rapid acceleration and deceleration of electron in aerials

C. Radio waves III. Inner shell electrons

D. X-rays IV. Klystron valve

Choose the correct answer from the option given below:

A-I, B-II, C-III, D-IV
A-IV, B-I, C-II, D-III
A-I, B-III, C-IV, D-II
A-IV, B-III, C-II, D-I

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(2)

1. Klystron valve used to produce Microwave

2. Gamma ray → Radioactive decay

3. Radio wave → Rapid acceleration and deceleration of electrons in aerials

4. X-ray → Inner shell electrons

Q 9 :

If a source of electromagnetic radiation having power 15 kW produces $10^{16}$ photons per second, the radiation belongs to a part of spectrum is (Take Planck constant $h = 6 \times 10^{- 34}$ Js) [2023]

Micro waves
Ultraviolet rays
Gamma rays
Radio waves

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(3)

$Energy of one photon = \frac{Power}{photon frequency}$

$E = h ν = \frac{15 \times 10^{3}}{10^{16}}$

$\Rightarrow ν = \frac{15 \times 10^{- 13}}{6 \times 10^{- 34}} = 2.5 \times 10^{21}$

Q 10 :

If $\vec{E}$ and $\vec{K}$ represent electric field and propagation vectors of the EM waves in vacuum, then magnetic field vector is given by ( $ω$ - angular frequency) [2023]

$\frac{1}{ω} (\vec{K} \times \vec{E})$
$ω (\vec{K} \times \vec{E})$
$\vec{K} \times \vec{E}$
$ω (\vec{E} \times \vec{K})$

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(1)

Magnetic field vector will be in the direction of $\vec{K} \times \vec{E}$

$Magnitude of B = \frac{E}{C} = \frac{K}{ω} E$

or $\vec{B} = \frac{1}{ω} (\vec{K} \times \vec{E})$

Q 11 :

Given below are two statements: [2023]

Statement I: Electromagnetic waves are not deflected by electric and magnetic field.

Statement II: The amplitude of electric field and the magnetic field in electromagnetic waves are related to each other as $E_{0} = \sqrt{\frac{μ_{0}}{ε_{0}}} B_{0}$

In the light of the above statements, choose the correct answer from the options given below:

Statement I is true but statement II is false
Both Statement I and Statement II are true
Statement I is false but statement II is true
Both Statement I and Statement II are false

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(1)

Statement-I is correct as EMW are neutral.

Statement-II is wrong.

$E_{0} = \sqrt{\frac{1}{μ_{0} ε_{0}}} B_{0}$

Q 12 :

The amplitude of magnetic field in an electromagnetic wave propagating along y-axis is $6.0 \times 10^{- 7} T$ . The maximum value of electric field in the electromagnetic wave is: [2023]

$5 \times 10^{14} {Vm}^{- 1}$
$180 {Vm}^{- 1}$
$2 \times 10^{15} {Vm}^{- 1}$
$6.0 \times 10^{- 7} {Vm}^{- 1}$

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(2)

$\frac{E}{B} = c$

$E = B C = 6 \times 10^{- 7} \times 3 \times 10^{8} = 18 \times 10$

$E = 180 {Vm}^{- 1}$

Q 13 :

Given below are two statement: one is labelled as Assertion A and the other is labelled as Reason R. [2023]

Assertion A: EM waves used for optical communication have longer wavelengths than that of microwave, employed in Radar technology.

Reason R: Infrared EM waves are more energetic than microwaves, (used in Radar)

In the light of given statements, choose the correct answer from the options given below:

A is false but R is true
A is true but R is false
Both A and R true but R is NOT the correct explanation of A
Both A and R true and R is the correct explanation of A

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(1)

Optical communication is performed in the frequency range of 1 THz to 1000 THz.

(Microwave to UV)

So, EM waves used for optical communication have shorter wavelength than that of microwaves used in RADAR.

Also, $ν_{infrared} > ν_{microwave}$

$∴$ Infrared EM waves are more energetic than microwave.

Q 14 :

Match List I with List II of Electromagnetic waves with corresponding wavelength range: [2023]

List I List II

A. Microwave I. 400 nm to 1 nm

B. Ultraviolet II. 1 nm to $10^{- 3}$ nm

C. X-Ray III. 1 mm to 700 nm

D. Infra-red IV. 0.1 m to 1 mm

Choose the correct answer from the options given below:

(A)-(I), (B)-(IV), (C)-(II), (D)-(III)
(A)-(IV), (B)-(I), (C)-(II), (D)-(III)
(A)-(IV), (B)-(II), (C)-(I), (D)-(III)
(A)-(IV), (B)-(I), (C)-(III), (D)-(II)

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(2)

Increasing order of wave length

X-ray — 1 nm to $10^{- 3}$ nm
Ultra Violet — 400 nm to 1 nm
Infra red — 1 mm to 700 nm
Micro wave — 0.1 m to 1 mm

Q 15 :

Match the LIST-I with LIST-II [2026]

List - I List - II

A. Radio-wave I. is produced by Magnetron valve

B. Micro-wave II. due to change in the vibrational modes of atoms

C. Infrared-wave III. due to inner shell electrons moving from higher energy level to lower energy level

D. X-ray IV. due to rapid acceleration of electrons

Choose the correct answer from the options given below:

A-II, B-IV, C-III, D-I
A-IV, B-II, C-I, D-III
A-IV, B-I, C-II, D-III
A-IV, B-III, C-I, D-II

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(3)

Radio wave ⇒ Produced by rapid acceleration of electrons
Microwave ⇒ By magnetron valve
Infrared wave ⇒ Change in vibrational modes
X ray ⇒ Transition of inner shell electrons from high energy level to low energy level.

A – IV, B – I, C – II, D – III

Topic Question Set

Q 1 :

Arrange the following in the ascending order of wavelength:

A. Gamma rays ( $λ_{1}$ )

B. x-rays ( $λ_{2}$ )

C. Infrared waves ( $λ_{3}$ )

D. Microwaves ( $λ_{4}$ )

Choose the most appropriate answer from the options given below [2024]

Q 2 :

Match List-I with List-II:

List-I

(EM-Wave)

List-II

(Wavelength Range)

A Infra-red (I) $10^{- 3}$ nm

B Ultraviolet (II) 400 nm to 1 nm

C X-rays (III) 1 mm to 700 nm

D Gamma rays (IV) 1 nm to $10^{- 3}$ nm

Choose the correct answer from the options give below [2024]

Q 3 :

Arrange the following in the ascending order of wavelength ( $λ$ )

(A) Microwaves ( $λ_{1}$ ) (B) Ultraviolet rays ( $λ_{2}$ )

(C) Infrared rays ( $λ_{3}$ ) (D) X-rays ( $λ_{4}$ )

Choose the most appropriate answer from the options given below: [2025]

Q 6 :

The electric field and magnetic field components of an electromagnetic wave going through vacuum is described by $E_{x} = E_{0} \sin (k z - ω t), B_{x} = B_{0} \sin (k z - ω t)$ . Then the correct relation between $E_{0}$ and $B_{0}$ is given by [2023]

Q 7 :

Match List-I with List-II. [2023]

List I List II

A. Microwaves I. Physiotherapy

B. UV rays II. Treatment of cancer

C. Infra-red rays III. Lasik eye surgery

D. X-rays IV. Aircraft navigation

Choose the correct answer from the option given below:

Q 9 :

If a source of electromagnetic radiation having power 15 kW produces $10^{16}$ photons per second, the radiation belongs to a part of spectrum is (Take Planck constant $h = 6 \times 10^{- 34}$ Js) [2023]

Q 10 :

If $\vec{E}$ and $\vec{K}$ represent electric field and propagation vectors of the EM waves in vacuum, then magnetic field vector is given by ( $ω$ - angular frequency) [2023]

Q 12 :

The amplitude of magnetic field in an electromagnetic wave propagating along y-axis is $6.0 \times 10^{- 7} T$ . The maximum value of electric field in the electromagnetic wave is: [2023]

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	List-I (EM-Wave)		List-II (Wavelength Range)
A	Infra-red	(I)	$10^{- 3}$ nm
B	Ultraviolet	(II)	400 nm to 1 nm
C	X-rays	(III)	1 mm to 700 nm
D	Gamma rays	(IV)	1 nm to $10^{- 3}$ nm

	List I		List II
A.	Microwaves	I.	Physiotherapy
B.	UV rays	II.	Treatment of cancer
C.	Infra-red rays	III.	Lasik eye surgery
D.	X-rays	IV.	Aircraft navigation

	List I		List II
A.	Microwave	I.	400 nm to 1 nm
B.	Ultraviolet	II.	1 nm to $10^{- 3}$ nm
C.	X-Ray	III.	1 mm to 700 nm
D.	Infra-red	IV.	0.1 m to 1 mm

	List - I		List - II
A.	Radio-wave	I.	is produced by Magnetron valve
B.	Micro-wave	II.	due to change in the vibrational modes of atoms
C.	Infrared-wave	III.	due to inner shell electrons moving from higher energy level to lower energy level
D.	X-ray	IV.	due to rapid acceleration of electrons

Topic Question Set

Q 1 : Arrange the following in the ascending order of wavelength: A. Gamma rays (λ1) B. x-rays (λ2) C. Infrared waves (λ3) D. Microwaves (λ4) Choose the most appropriate answer from the options given below [2024]

Q 2 : Match List-I with List-II: List-I (EM-Wave) List-II (Wavelength Range) A Infra-red (I) 10-3nm B Ultraviolet (II) 400 nm to 1 nm C X-rays (III) 1 mm to 700 nm D Gamma rays (IV) 1 nm to 10-3 nm Choose the correct answer from the options give below [2024]

Q 3 : Arrange the following in the ascending order of wavelength (λ) (A) Microwaves (λ1) (B) Ultraviolet rays (λ2) (C) Infrared rays (λ3) (D) X-rays (λ4) Choose the most appropriate answer from the options given below: [2025]

Q 5 : If an optical medium possesses a relative permeability of 10π and relative permittivity of 10.0885, then the velocity of light is greater in vacuum than that in this medium by _______ times. (μ0=4π×10–7H/m, ∈0=8.85×10–12F/m, c=3×108m/s) [2025]

Q 6 : The electric field and magnetic field components of an electromagnetic wave going through vacuum is described by Ex=E0sin(kz-ωt),Bx=B0sin(kz-ωt). Then the correct relation between E0 and B0 is given by [2023]

Q 7 : Match List-I with List-II. [2023] List I List II A. Microwaves I. Physiotherapy B. UV rays II. Treatment of cancer C. Infra-red rays III. Lasik eye surgery D. X-rays IV. Aircraft navigation Choose the correct answer from the option given below:

Q 9 : If a source of electromagnetic radiation having power 15 kW produces 1016 photons per second, the radiation belongs to a part of spectrum is (Take Planck constant h=6×10-34Js) [2023]

Q 10 : If E→ and K→ represent electric field and propagation vectors of the EM waves in vacuum, then magnetic field vector is given by (ω- angular frequency) [2023]

Q 12 : The amplitude of magnetic field in an electromagnetic wave propagating along y-axis is 6.0×10-7 T. The maximum value of electric field in the electromagnetic wave is: [2023]

Q 14 : Match List I with List II of Electromagnetic waves with corresponding wavelength range: [2023] List I List II A. Microwave I. 400 nm to 1 nm B. Ultraviolet II. 1 nm to 10-3 nm C. X-Ray III. 1 mm to 700 nm D. Infra-red IV. 0.1 m to 1 mm Choose the correct answer from the options given below:

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Q 1 :

Arrange the following in the ascending order of wavelength:

A. Gamma rays ( $λ_{1}$ )

B. x-rays ( $λ_{2}$ )

C. Infrared waves ( $λ_{3}$ )

D. Microwaves ( $λ_{4}$ )

Choose the most appropriate answer from the options given below [2024]

Q 2 :

Match List-I with List-II:

List-I

(EM-Wave)

List-II

(Wavelength Range)

A Infra-red (I) $10^{- 3}$ nm

B Ultraviolet (II) 400 nm to 1 nm

C X-rays (III) 1 mm to 700 nm

D Gamma rays (IV) 1 nm to $10^{- 3}$ nm

Choose the correct answer from the options give below [2024]

Q 3 :

Arrange the following in the ascending order of wavelength ( $λ$ )

(A) Microwaves ( $λ_{1}$ ) (B) Ultraviolet rays ( $λ_{2}$ )

(C) Infrared rays ( $λ_{3}$ ) (D) X-rays ( $λ_{4}$ )

Choose the most appropriate answer from the options given below: [2025]

Q 6 :

The electric field and magnetic field components of an electromagnetic wave going through vacuum is described by $E_{x} = E_{0} \sin (k z - ω t), B_{x} = B_{0} \sin (k z - ω t)$ . Then the correct relation between $E_{0}$ and $B_{0}$ is given by [2023]

Q 7 :

Match List-I with List-II. [2023]

List I List II

A. Microwaves I. Physiotherapy

B. UV rays II. Treatment of cancer

C. Infra-red rays III. Lasik eye surgery

D. X-rays IV. Aircraft navigation

Choose the correct answer from the option given below:

Q 9 :

If a source of electromagnetic radiation having power 15 kW produces $10^{16}$ photons per second, the radiation belongs to a part of spectrum is (Take Planck constant $h = 6 \times 10^{- 34}$ Js) [2023]

Q 10 :

If $\vec{E}$ and $\vec{K}$ represent electric field and propagation vectors of the EM waves in vacuum, then magnetic field vector is given by ( $ω$ - angular frequency) [2023]

Q 12 :

The amplitude of magnetic field in an electromagnetic wave propagating along y-axis is $6.0 \times 10^{- 7} T$ . The maximum value of electric field in the electromagnetic wave is: [2023]